長期以來，公營事業所擁有公共性和企業性的雙重性格一直是爭議的焦點。隨著時代和環境的不同，公營事業的存廢與否也成了另一個新的議題，而這又牽涉到民營化後在企業性發揮下是否能兼顧到公共性的問題。 日本三公社的民營化經常被譽為是成功的民營化事例。因而本文欲以日本的民營化為主體，首先釐清日本的民營化概念。其次，從學理來探討公共性和企業性的意涵，進而將焦點限縮至民營化企業，討論民營化後所謂公共性和企業性的構成要素，並嘗試給予其較明確的定義，以作為日後檢討、評估民營化時的參考。

For long, the double properties of public and corporate natures ii1vested in state businesses have remained controversial. Along with the changes of era and environment, the preservation and abolishment of state businesses have also turned into another new issue; meanwhile, such issue also involves whether the public property can be covered under corporate mechanism after privatization. The privatization of Japan's three major state businesses has often been deemed as successful cases. Therefore, this study proposes basing on the privatization of Japan in delineating Japan's concept of privatization first, followed by exploring the meanings of public and corporate properties from theoretical perspective for further narrowing the focus on private corporations in discussing the so called the essential elements that constitute the public and corporate properties after privatization. Attempts are also made in endowing clearer definition for future reference in evaluating, reviewing privatization.